Power cables are used at airports to supply electrical power to airplanes when they are on the ground. A common power cable system includes a cable of a length of about 21 meters (69 feet) which extends from a storage bin through a motor-driven retriever located about four meters (12 feet) above the ground, and down along the ground to a connector at the outer end which can plug into a correponding connector on the aircraft. In freezing weather airplanes are commonly sprayed with glycol, an anti-freeze solution to prevent ice buildup. As a result, the ground area around the aircraft becomes coated with the slippery glycol fluid, and cables lying on the ground also pick up considerable fluid. A prior power-driven retriever may include a pair of rubber wheels which rotate about vertical axes and which can grip a power cable between them. The prior power cables have a cross section with numerous bumps caused by various conductors near the periphery of the cable. When the cable becomes covered with slippery anti-freeze fluid, the retrieval mechanism has often slipped on the cable so the cable could not be retracted. A retrieval system which reliably gripped a cable to assure its retrieval even when the cable is covered with a slippery fluid, would be of considerable value.